REMOTE CONTROL OF DEVICES USING CELLPHONES Shuhab-u-Tariq (1SI03EC109)

INTRODUCTION Telephone operated device control circuit which enables switching ON & OFF of appliances through telephone lines. It senses the telephone ring. Automatically switches call to this system, after pre-defined rings. Switches ON/OFF the load depending upon the key pressed by the caller.

BASIC BLOCK DIAGRAM

RING DETECTOR & SCHMITT TRIGGER SECTION

RING COUNTER CUM SWITCHING UNIT This Section counts the number of rings and lifts the cradle automatically after pre-defined number of rings. IC 4017 is used to count the number of rings. The triggering action is carried out by relay driver circuit, which comprises of two Darlington transistors with a relay.

IC 4017 DECADE COUNTER Q1 Q2 Q6 RESET CLOCK Q7 Q5 11 9 12 13 14 15 16 CLOCK ENABLE COUT Q9 Q4 Q8 Q7 C0 Q0 Q5 R CK CE +Vcc IC 4017 DECADE COUNTER 11 9 12 13 14 15 16 8 7 6 5 4 3 2 1 10 GND

CIRUIT DIAGRAM OF RING COUNTER CUM SWITCHING & CONTROLLING UNIT 3 Q0 2 Q1 4 Q2 7 Q3 10 Q4 1 Q5 5 Q6 6 Q7 9 Q8 11 Q9 R2 R3 R1 16 IC1 4017 15 13 14 S1 +5 V CLOCK INPUT from Schmitt Trigger RESET SWITCH D1 8 TR1 R4 TR2 N/O N/C +12V RLC1 R5 D2 LED To Telephone Line RING COUNTER SECTION SWITCHING SECTION CIRUIT DIAGRAM OF RING COUNTER CUM SWITCHING & CONTROLLING UNIT

DTMF DECODER & BCD TO BINARY CONVERTER MODULE DTMF – Dual Tone Multiple Frequency Resultant signal of two tones at the same time for any key pressed f(t) = Asin(2*П*fa*t) + Bsin(2*П*fb*t)

Pin Diagram of MT8870

Pin Diagram of IC 74154

DTMF to Binary converter

Function Decode Table

LATCH & LOAD DRIVER SECTION This section executes the command send by caller by latching the load to previous state on/off. Terms and components used here: D flip-flop - It is incorporated in IC4013 2003-driver IC- High voltage and high current driver IC is used to drive low impedance relay.

D flip flop an overview D Q CLOCK TRANSIENT DATA SINCE LAST POSITIVE GOING CLOCK DATA HELD IN LATCH STATE OF D INPUT CLOCKED TO Q OUTPUT ON RISING CLOCK EDGE FIG 3

Timing diagram 1 D INPUT CLOCK INPUT Q OUTPUT TIME FIG 4

IC 4013 VCC Q2 IN.Q2 CLK2 RST2 D2 SET2 Q1 IN.Q1 CLK1 RST1 D1 SET1 GROUND D.CHAR THERS C.VTG RST 1 O/P1 TRGER GROUND 14 13 12 11 10 9 8 1 2 3 4 5 6 7

CIRCUIT DIAGRAM Sw1 Q1 Q2 Q3 Q4 IC3 RL1 RL2 RL3 RL4 to Telephone Line 14 9 13 11 12 IC1B 8 6 7 IC3 2 1 4 3 5 15 16 100 GND IC1A 10 IC2B Q IC2A R1 +5V +12V N/O N/C Sw1 RL1 RL2 RL3 RL4 to Telephone Line Q3 Q4 Input signlas

POWER SUPPLY UNIT X 1 +12V 9V +5V 230AC C1 C2 C3 C4 IC1 7812 7805 D11

CONCLUSION Low power consumption, and compact in size. From any distance appliances can be controlled, overcoming the limited range of infra-red and radio remote control. High reliability, due to the usage of semi conductors.